A mutants-among-us sf/thriller hybrid--with a profuse, involved, but often flimsy and foolish plot. Thanks to a radioactive meteorite that fell in the 11th century, a small, secret band of mutants has arisen in Earth's population: the rather unoriginal Riis, who come in three varieties--sarnit, melior, and kivtle. Pollution is rendering the Riis sterile, however, so to continue the race they've developed a chemical to mutate ordinary humans into Riis. Paul Lerner, melior head of the mistrustful Riis council, recommends the chemical's use; sarnit chief Sviridoff opposes him (since the chemical mutants will be either melior or kirtle, but not sarnit), declaring war on the melior; the kivtle remain aloof. But then a supragovernmental organization, PEG, dedicated to icing the foes of capitalism, discovers the existence of the Riis (despite the heroics of melior double agent Bishop), while the chemical (due to self-destruct in a few days) falls into the hands of bewildered human journalist Peter Stillman. PEG, sarnit, and melior converge on Stillman, there's murder, mayhem, torture, betrayal, rescue, and pursuit; and, meanwhile, Lerner's young son Tommy, who has powers no one suspects, is making plans of his own to deal with the chemical. Fluently written, but--with an unpersuasive background (supposedly the US today) and essentially unsympathetic protagonists (the murderous Rils)--this ends up a tangled, implausible melodrama with only a few engaging notions.